Method of pulling a well liner



Nov. 16, 1965 s. WINGER METHOD OF PULLING A WELL LINER Filed 001;. v, 1965 W M W. W A A M a 6 7 //W//JIU 7 M 5 1M w 0 v a 4+" m, M l l wmw f 3,217,803 METHOD OF PULLING A WELL LINER Sam L. Winger, Taft, Calif., assignor to Midway Fishing Tool (10., Long Beach, Calif., a corporation of California Filed Oct. 7, 1963, Ser. No. 314,275 Claims. (Cl. 166-46) This invention relates to the art of recovering a well liner from a well and it is a particular object of the invention to provide a method of and apparatus for pulling a well liner to recover the latter after it has been in use long enough for the surrounding formation to have settled against the liner and make the removal thereof fairly difiicult.

These liners are perforated to allow the oil to enter from the formation, and are generally several hundred feet or more in length. When completing the well, the liner is suspended by a liner hanger within the lower portion of the well casing and remains there during the production of oil from the well as long as the liner functions properly. The withdrawal of a liner which has been in operation in a well for some time, presents a considerable problem and heretofore has required the use of very expensive special equipment and a highly skilled crew for accomplishing this task.

It is another object of the present invention to provide a method of and apparatus for pulling a well liner which will permit this being done by production crews of ordinary skill and without needing any expensive or specially developed equipment.

The manner of accomplishing the foregoing objects as well as further objects and advantages will be made manifest in the following description taken in connection with the accompanying drawings in which:

FIG. 1 is a diagrammatic vertical sectional view of a well including a well casing and a liner installed in said well, and shows, in elevation, a preferred embodiment of the apparatus of the invention as this is positioned in said well at the beginning of its use in performing the method of the present invention.

FIG. 2 is an enlarged horizontal sectional view taken on the line 22 of FIG. 1 and illustrates the rotary valve of the apparatus of the invention.

FIG. 3 is a vertical sectional view taken on the line 3-3 of FIG. 2 and illustrates the packer and the valve of said apparatus with the latter in closed position.

FIG. 4 is an enlarged horizontal sectional view taken on the line 44 of FIG. 1 and illustrates the manner in which the formation is packed around the liner when the apparatus of the invention is first inserted into the well as shown in FIG. 1.

FIG. 5 is a view similar to FIG. 4 and illustrates the manner in which the formation is expanded by the introduction of liquid under high pressure into said liner during the performance of the method of this invention so as to free the liner from said formation and permit the same to be withdrawn from the well.

Referring specifically to the drawings, the apparatus or tool of the invention is seen in FIG. 1 as being installed in an oil well 11 having a main casing 12 in a lower end portion of which a perforated liner 13 has been suspended on a liner hanger 14. The liner 13 is installed in the well 11 for the purpose of producing oil from the oil bearing formation 15 located below the lower end of the main casing and surrounding the downwardly extending portion of the liner.

As clearly shown in FIGS. 1 and 4 solid matter 16 from the oil bearing formation 15 has settled around the liner 13 while it has been in use so as to be packed against the liner and thus resist efforts made to remove the liner from the well.

The apparatus 10 is suspended at its upper end on a drill string 17 by a pin and box connection 18 between the drill string and the mandrel 19 of a rotary valve 20 which is embodied in said apparatus. The mandrel 19 is tubular, having an internal bore 25 of the same diameter as the passage in drill string 17, this mandrel also having an annular flange 26 near its upper end and external threads 27 on a lower portion thereof. The portion of mandrel 19 between flange 26 and threads 27 provides a cylindrical surface on which a rotary valve sleeve 28 is mounted. Fixed in a suitable hole provided in annular flange 26 and extending lengthwise therefrom is a limit pin 29, this pin being received in a recess 30 formed in an adjacent end of sleeve 28, the connection between said pin and recess permitting sleeve 28 freedom to rotate on mandrel 19 only between open and closed positions of the valve 20. When said sleeve is in open position, a radial hole 31 provided in mandrel 19 and a radial hole 32 provided in sleeve 28 are in alignment so as to cause the bore 25 to communicate freely with the space outside the tool 10. When the sleeve 28 is in closed position, holes 31 and 32 are out of alignment and thus communication between bore 25 and the exterior of the tool is shut off by the valve 20.

Mounted to extend radially from the sleeve 28 at four equally spaced positions thereabout are four radially expansive pressure devices 33 which are provided for the purpose of engaging the inner face of well casing 12 when the tool 10 is extended downwardly therein to retard rotation of valve sleeve 28 and thus permit valve 20 to be readily controlled by rotation of the drill string 17 from the top of the well. Each of the devices 33 is mounted in a recess 34 formed lengthwise in the periphery of sleeve 28 and comprises a pressure bar 35 in which are mounted four coil springs 40 which constantly yieldably expand the bar radially outwardly. Limit fittings 41, held by screws 42 in opposite ends of recesses 34, limit the radial distance outwardly which the springs 40 may expand the bars 35.

The tool 10 also includes a packer mandrel 44 having a box end 45 which is internally threaded to match the threads 27 of the mandrel 19 which is screwed into box end 45 so that the latter serves to hold rotary valve sleeve 28 assembled on the valve mandred 19. The packer mandrel 44 is turned down to form an annular packer shoulder 46 and a cylindrical surface 47 adjacent thereto for receiving an annular rubber packer 48. The surface 47 terminates at its lower end in threads 49 for receiving nuts 50 and 51 which hold the packer 48 on surface 47. The packer 48 has a peripheral cylindrical surface 55 which slidably fits Within the inside diameter of the casing 12, and the lower edge of the packer 48 has a pressure seal forming annular fin 56 which is adapted to expand into tight sealing engagement with the casing when liquid under pressure is delivered into the space beneath this packer.

The packer mandrel 44 is provided with an internal bore 57 which is the same size as bore- 25 of mandrel 19.

A short distance below the nut 51, the packer mandrel 44 makes a threaded pin and box connection 58 with the upper end of the operating mandrel 59 of a conventional rotary releasing spear 60. This spear may be any of various rotary releasing spears provided in the oil industry to be inserted in a liner to be withdrawn from the well and operable by rotation of the drill string to engage or disengage the liner at will. The spear 60 shown in the drawings is a patented Shaffer-Harmon rotary releasing spear which is illustrated and described on page 3496 of vol. 2 of the 1946-47 composite catalogue of oil field and pipeline equipment published by The Oil Weekly. Inasmuch as the details of construction of the spear 60 are thus an established part of the prior art, a description herein of these details will be dispensed with.

Operation It might be noted however that the spear 60 has three equally spaced circumferentially columns of slips 61 which are retracted out of contact with the liner 13 when the spear 60 is in its retracted condition and are expanded into biting relation with the inner surface of said liner when said spear is in its expanded condition, and the spear till is shown in the latter condition in FIG. 1 of the drawings. This view shows the tool 10 after it has been inserted downwardly through the casing 12 on the lower end of the drill string 17 until it has reached the position shown in this view and the drill string then rotated so as to operate the spear 60 to set the slip 61 thereof against the inner surface of the liner 13 and also so as to close the valve 20 which had been left open during the descent of the tool through the casing 12. It is of course to be understood that the well 11 is preferably filled with circulating liquid at the start of the operation and the tool 10 is submerged in this liquid throughout said operation.

At the upper end of the oil well 11, the drill string 17 is suspended on the usual hook and block or it may be suspended by slips on the derrick floor.

Owing to the close fit which the packer 48 makes with the inner surface of the main casing 12, the circulating liquid displaced by the tool 10 and drill string 17 as these descend in the well flows upwardly through the central bore 62 of spear 61}, the bores 57 and 25 of mandrels 44 and 19 and out through the holes 31 and 32 of valve 20 into the space between the drill string 17 and casing 12 above the packer 48.

When the tool 10 reaches the level at which it is shown in FIG. 1, the spear 60 is set against the inner surface of the perforated liner 13 and the rotary valve 20 is closed. The circulating pumps are then started so as to force circulating liquid downwardly through the tool 10 and out of the lower end of the spear 60 until this causes a sharp increase in the hydraulic pressure prevailing within the perforated liner 13 and throughout the space extending upwardly from this liner to the lower end of the packer 48 which of course expands into tight sealing relation with the casing 12 responsive to the increase in hydraulic pressure therebelow so as to prevent any of the liquid thus pumped into the liner from escaping upwardly past this packer.

For the purposes of this invention in the experience with it in the field to date, a pressure of 400 lbs. per sq. in. maintained within the perforated liner 13 for a period of from a few minutes to three hours has been found amply sufficient to produce an expansion radially of the solid matter 16 packed around the liner 13 as shown in FIG. 4 until this has separated from the outer surface of the liner as diagrammatically shown in FIG. so as to leave the liner free from frictional engagement with this solid matter for withdrawal from the well by lifting on the drill string 17. A sleeve of liquid 63 thus is formed which lubricates the liner during its withdrawal from the mass of solids 16.

It has also been noted that the hydraulic pressure built up and maintained within the perforated liner 13 for a suflicient period to expand the solid matter 16 from packed relation with the liner, develops an upward thrust on the packer 48 itself which contributes substantially to the lifting force being applied by the hoist to the drill string 17 for upward withdrawal of the liner. Although expanded tightly against the inner face of the casing 12, the rubber packer 48 is still slidable therein and yields upwardly as the packed solid matter 16 increasingly has its bond broken with the outer surface of the liner 13. By watching his pressure gauge and weight gauge the rig operator is able to observe the increasing ease with which the liner 13 yields to the tension applied to the drill string and thus knows when the liner has been freed sufliciently by the sustained hydraulic pressure delivered thereto by the present method, to effect a speeding up of the withdrawal of the liner so as to promptly consummate the latter.

Generally, in the performance of the method of this invention, it is preferable to hold the liquid in the liner under high pressure until the liner has been sufficiently freed from solid matter packed thereabout that the lqiud pressure may be brought back to normal thus allowing the packer 48 to retract to its normal diameter and be free from expansive action of the liquid thereagainst during the step of lifting on the drill string 17 for withdrawal of the liner from the well. In this way the packer 48 readily passes over casing joints and other irregularities on the inner surface of the casing which might otherwise impede withdrawal of the liner.

The aforesaid withdrawal step of the method of the invention may advantageously proceed in a series of withdrawal stages each of which causes a decrease in said pressure, said stages being separated by pauses, during each of which said hydraulic pressure is built up again to keep said formation solids expanded away from said liner.

While only a single embodiment of the method and apparatus of the present invention has been disclosed in the present specification and drawings, it is to be understood that various changes and modifications might be made in these without departing from the spirit of the invention or the scope of the appended claims.

The claims are:

1. A method of pulling a perforated liner from an oil well having a main casing and wherein solids of the formation surrounding the liner have become packed thereagainst, said method comprising the steps of introducing a drill string into said well carrying spear means and a packer spaced thereabove and slidably related to said casing to form a piston therein, extending said spear means into said liner while said packer remains above the upper end of said liner, manipulating said drill string to actuate said spear means to engage said liner for pulling upwardly thereon, pumping liquid downwardly through said drill string and said packer and into said liner to force liquid outwardly through the perforations of said liner at a sufficient pressure and for a sufficient period of time to expand said formation solids out of frictional engagement with said liner, while simultaneously applying said liquid pressure to the bottom face of said packer, thereby producing an upward lifting force tending to lift said liner, and applying to said drill string whatever additional lifting force is required, when the formation expanding action aforesaid has progressed substantially, to withdraw said liner and packer upwardly through said casing and out of said well.

2. A method as recited in claim 1 wherein said applied hydraulic pressure is substantially relaxed prior to undertaking the final step of withdrawing said packer and liner from said casing.

3. A method as recited in claim 1 wherein said final withdrawal step is started while said formation and piston packer are subjected to said high hydraulic pressure and said withdrawal step proceeds in a series of withdrawal stages, each of which causes a decrease in said pressure, said stages being separated by pauses, during each of which said hydraulic pressure is built up again to keep said formation solids expanded away from said liner.

4. A method of pulling a perforated liner from an oil Well having a main casing and wherein solids of the formation surrounding the liner have become packed thereagainst, said method comprising the steps of packing off the lower portion of said casing in which said liner is suspended at a point above the upper end of the liner, pumping liquid downwardly into said packed off area and into said liner to force liquid outwardly through the perforations of said liner at a sufiicient pressure and for a sufficient period of time to substantially expand said formation solids out of frictional engagement with said liner, and then lifting upwardly on said liner to withdraw the same from said well.

6 5. A method as recited in claim 4 wherein said applied hydraulic pressure is substantially relaxed prior to undertaking the final step of withdrawing said liner from the well.

References Cited by the Examiner UNITED STATES PATENTS 2,149,417 3/1939 Brown 166-46 2,190,442 2/1940 Costello 166-98 2,377,249 5/1945 Lawrence 166-98 2,724,440 11/1955 Moore 166-46 2,734,581 2/1956 Bonner 166-98 2,806,534 9/1957 Potts 166-98 2,817,555 12/1957 Le Bus 166-46 2,915,126 12/1959 Potts 166-98 2,973,038 2/1961 Segelhorst 166-98 CHARLES E. OCONNELL, Primary Examiner. 

4. A METHOD OF PULLING A PERFORATED LINER FROM AN OIL WELL HAVING A MAIN CASING AND WHEREIN SOLIDS OF THE FORMATION SURROUNDING THE LINER HAVING BECOME PACKED THEREAGAINST, SAID METHOD COMPRISING THE STEPS OF PACKING OFF THE LOWER PORTION OF SAID CASING IN WHICH SAID LINER IS SUSPENDED AT A POINT ABOVE THE UPPER END OF THE LINER, PUMPING LIQUID DOWNWARDLY INTO SAID PACKED OFF AREA AND INTO SAID LINER TO FORCE LIQUID OUTWARDLY THROUGH THE PERFORATIONS OF SAID LINER AT A SUFFICIENT PRESSURE AND FOR A SUFFICIENT PERIOD OF TIME TO SUBSTANTIALLY EXPAND SAID FORMATION SOLIDS OUT OF FRICTIONAL ENGAGEMENT WITH SAID LINER, AND THEN LIFTING UPWARDLY ON SAID LINER TO WITHDRAW THE SAME FROM SAID WELL. 